Motor cortex stimulation (MCS) is a promising clinical technique for treatment of chronic pain. However, optimization of the therapeutic efficacy is hampered since it is not known how electrically activated neural structures in the motor cortex can induce pain relief. Furthermore, multiple neural elements are present in the motor cortex such as cell bodies, dendrites and axons which are parallel or perpendicular to the cortical layers. Which of these neural elements are immediately excited by the electrical pulses in MCS depends on positioning of anodal and cathodal electrodes and stimulation parameters. A proper insight on these effects would be useful for peroperative decision making on electrode positioning and for the interpretation of stimulation results after implantation. Computational modeling studies can help to identify the effects of electrical stimulation on cortical neural tissue, elucidate mechanisms of action and ultimately to optimize the therapy